Device Location Using LiveData Architecture Component

Android application.

I had a problem with implementing location detection logic without breaking Android application architecture.

After a couple of hours of researching, I finally came up with a solution to monitor the current location with LiveData usage. This article is a step by step solution to the above-stated problem.

Step 1. Add dependencies for location listener in Gradle module

implementation 'com.google.android.gms:play-services-location:x.x.x'

Step 2. Create Location Listener

class LocationListener private constructor(private val context: Context): LiveData<Location?>()

Inherit the class from LiveData

LiveData is an observable data holder class. Unlike a regular observable, LiveData is lifecycle-aware, meaning it respects the lifecycle of other app components, such as activities, fragments, or services. This awareness ensures LiveData only updates app component observers that are in an active lifecycle state.

Next is a full example of the Location Listener class:

class LocationListener private constructor(private val context: Context): LiveData<Location?>() {
    var requestingLocationUpdates: Boolean = true
    private var mFusedLocationClient: FusedLocationProviderClient? = null
    private var mLocationRequest: LocationRequest? = null

    @Synchronized
    private fun createLocationRequest() {
        Log.d(TAG, "Creating location request")
        mLocationRequest = LocationRequest.create()
        mLocationRequest?.interval = 20000
        mLocationRequest?.fastestInterval = 5000
        mLocationRequest?.priority = LocationRequest.PRIORITY_HIGH_ACCURACY
    }

    fun startService() {
        onActive()
    }


    override fun onActive() {
        super.onActive()
        if (ActivityCompat.checkSelfPermission(
                context, Manifest.permission.ACCESS_FINE_LOCATION
           ) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(
                context,
                Manifest.permission.ACCESS_COARSE_LOCATION
            ) != PackageManager.PERMISSION_GRANTED
        ) {
            return
        }
        fusedLocationProviderClient
        createLocationRequest()
        val looper = Looper.myLooper()
        mFusedLocationClient?.requestLocationUpdates(mLocationRequest, mLocationCallback, looper)
    }

    override fun onInactive() {
        if (mFusedLocationClient != null) {
            mFusedLocationClient?.removeLocationUpdates(mLocationCallback)
        }
    }

    val fusedLocationProviderClient: FusedLocationProviderClient?
        get() {
            if (mFusedLocationClient == null) {
                mFusedLocationClient = LocationServices.getFusedLocationProviderClient(context)
            }
            return mFusedLocationClient
        }

    private val mLocationCallback: LocationCallback = object : LocationCallback() {
        override fun onLocationResult(locationResult: LocationResult) {
            val newLocation = locationResult.lastLocation
            if (newLocation != null && requestingLocationUpdates){
                value = newLocation
                onInactive()
            }
        }
    }

    companion object {
        private const val TAG = "LocationListener"
        private var instance: LocationListener? = null
        fun getInstance(appContext: Context): LocationListener? {
            if (instance == null) {
                instance = LocationListener(appContext)
            }
            return instance
        }
    }

}

So what we did basically:

  • build FusedLocationProviderClient
  • build location callback
  • build location request
  • create looper
  • request location updates

After we start requesting location updates this will tell the GoogleServices to let the app know whenever there’s a location change. In this example, I disabled location updating after it will found.

override fun onLocationResult(locationResult: LocationResult) {
            val newLocation = locationResult.lastLocation
            if (newLocation != null && requestingLocationUpdates){
                value = newLocation
                onInactive() //Disable location updating
            }
        }

It is possible to use Location Listener in ViewModel to make it easier to use the result of location services.

The ViewModel class is designed to store and manage UI-related data in a lifecycle conscious way. The ViewModel class allows data to survive configuration changes such as screen rotations.

Example:

class LocationVM: ViewModel() {

    var location: MutableLiveData<Location>? = MutableLiveData<Location>()
    var locationRepository: LocationListener? = null

    fun setLocationRepository(context: Context) {
        locationRepository = LocationListener.getInstance(context)
    }

    fun enableLocationServices(){
        locationRepository?.let {
            it.startService()
        }
    }
}

Step 3. To make this works we should create observers

Observer for the listener:

viewModel.locationRepository?.let {
    if (!it.hasObservers()) {
        it.observe(this, Observer<Location?> { location ->
            location?.let {
                viewModel.location?.value = it
                progress_bar.visibility = View.INVISIBLE
            }
        })
    }
}

Observer for mutable live data:

val locationObserver = Observer<Location> { location ->
    // Update the TextView "location_text" text
    Log.i("LiveData location", "" + location.latitude + " / " + location.longitude)
    location?.let {
        location_text.text = "" + it.latitude + "\n" + it.longitude
    }
}
viewModel.location?.observe(this, locationObserver)

And that’s it.

How Observers Work in Android Applications.

Check out an example project on GitHub.

Mobile App Development.
Digital-Only Banking App

What You Should Know Before Building Digital-Only...

What You Should Know Before Building...

What You Should Know Before Building Digital-Only Banking App

Cash is becoming obsolete as the traditional financial system actively adopts modern technologies. Users watch how innovative solutions like Apple...

Android CI/CD boilerplate for publishing via Fastlane

How to Automate CI/CD for Android App with Boilerplate

How to Automate CI/CD for Android App...

How to Automate CI/CD for Android App with Boilerplate

Stop publishing your Android apps manually and start doing this fully automated at any stage.Mobile development, as well as any other software...

Progressive Web App PWA vs. Native App: Which One to Choose.

Progressive Web App PWA vs. Native App: Which One to...

Progressive Web App PWA vs. Native...

Progressive Web App PWA vs. Native App: Which One to Choose?

The current pace of life is not comparable to twenty years ago. And current technologies do not stand still. Every day people are seeking ways to...